The present invention relates to a system for maintaining data stored on a data medium secure against unauthorized copying and use. Specifically, an encrypted data medium is provided which includes a self contained apparatus for generating a decrypting key for decrypting the stored data from information read from the data medium.
The explosion of digital data technology has produced a demand for mass marketed data media in the form of optical disks and magnetic tapes which include program information other than computer software stored as digital data. These mass produced memory devices may contain audio or video records which are often used on equipment such as CD players and audio tape players which are not equipped with any type of security device which will prevent unauthorized copying. The ability to prevent the manufacture and use of illicit copies of these recordings has been a serious problem for the legitimate owners of the underlying copyrighted works. The source of illicit copying is from both home copying and commercial piracy. The availability of home recording devices permits on a very limited scale the manufacture of copies which diminish the market for the legitimate copies. While a single home copier will not individually create a large number of copies, it is expected that copying equipment will be so widespread that the total number of home copies will be very significant to the loss of commercial sales.
A related and potentially more serious threat to the legitimate producer of video and audio recordings is commercial piracy. The profit potential for illicit copies is so great that the threat of criminal sanctions, confiscation of plant and equipment has failed to deter these activities. For this reason, a system which will protect against copying and illicit use, and which does not rely upon a separate hardware device to be separately connected to the data reading hardware is desirable.
Security against copying of mass marketed data mediums may be increased by encrypting the data before recording on the medium, and further enhanced by changing the encryption key for each title, as well as for individual data frames of each title, frustrating any efforts to determine a universal decryption key. In order to provide such enhanced security, the keys for each title and each frame within a title must be supplied with the data medium in an undiscoverable form
A body of technology has developed for maintaining digital data such as computer software stored on a data medium, which is also the subject of wide spread copying piracy, inaccessible to unauthorized users. One common solution used to frustrate unauthorized use and copying of consumer software includes the provision of a hardware device mounted to a port of the computer which executes the software. During execution of the software, data which is necessary for the execution to proceed is recovered from the hardware device which may be a ROM. Unless the hardware device is possessed by the software user, the program cannot be executed. Duplicates of the software, therefore, are not usable without the corresponding ROM.
Adapting these measures to the problem of copying video and audio disks and magnetic tapes requires that a separate hardware device be provided with the encrypted software in order to recover the key necessary to decrypt the video or audio disk. The device must be difficult to replicate or analyze, and be capable of supplying the needed decryption keys on a title by title and a frame by frame basis to allow an authorized user to use the data.